https://likumi.lv/doc.php?id=222147

Latvia

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National regulation (government)

F B and C category permit is the quantity of pollutants that will be created during the operation phase. For every HRS (including or not including the on–site production) it is necessary to receive atleast C category permit. 
For Gas refuelling stations it is necessary to receive C category permitt
B category permit is necessary to obtain if:
petrol stations with 2 000 or more cubic metres of fuel per year (the total largest amount of fuel pumped during the last three years)
If the hydrogen is produced on–site using steam methane reforming and the rated thermal input is from 5 to 50 megawatts, if biomass (also wood and peat) or gaseous fuels are used in the combustion installation.
For storage units: 4.2. installations for the storage of unpacked organic or inorganic chemical substances, chemical products or intermediary products, if one tonne or more is stored, for the storage of enzymes – 20 tonnes or more.
By exceeding these thresholds it is necessary to obtain A category permit